<template>
<div>
  <div class="subject" v-for="item,index in arr" :key="index">
    <span>{{ item.num1 }}</span>
    <span>+</span>
    <span>{{ item.num2 }}</span>
    <span>=</span>
    <input type="number" ref="ipt"/>
    <button @click="submit(index)" >提交</button>
  </div>
</div>
</template>

<script>
export default {
  props:{
    arr:{
      type:Array,
      required:true
    }
  },
  data(){
    return {
      result:''
    }
  },
  methods:{
    submit(i){
      this.$emit('submit',i,this.$refs.ipt[i].value)
    }
  }

};
</script>

<style scoped>
.subject {
  margin: 5px;
  padding: 5px;
  font-size: 20px;
}
.subject span {
  display: inline-block;
  text-align: center;
  width: 20px;
}
.subject input {
  width: 50px;
  height: 20px;
}
</style>